Patent Grant
5612403
This application is related to U.S. patent application Ser. No. 07/843,738; Filed Feb. 28, 1992, abandoned. The present invention relates to a flexible die attach adhesive. The flexible die adhesive can be modified to be capable of developing very good adhesive strength at low curing temperatures. One embodiment of the invention relates to flexible card for processing in a computer that includes a semiconductor device enveloped therein adhered to a substrate by the aforementioned adhesive. As uses for semiconductor devices continue to increase there is a growing demand for adhesive compositions and formulations capable of securing semiconductor devices to substrates under a variety of conditions. The wide variety of applications using semiconductor devices sometimes require that such adhesive formulations be flexible where the device must be flexible and sometimes that the adhesive formulation be capable of developing very good adhesive strength at low curing temperatures so that significant stress is not imparted to the die and the curing conditions do not adversely affect other components. To improve workability, a modified adhesive formulation as described above but of low viscosity is also desirable. One application employing semiconductor devices which is gaining increasing importance is in the field of cards to be processed in computers where such cards incorporate one or more semiconductor devices and are therefore able to store more information than magnetic cards. Such cards may be useful over a broad spectrum of applications including, for example, credit and telephone cards. These cards, which are referred to as "smart cards" must be thin and must be able to bend without breaking, i.e., the card and card components must be flexible. Typically, "smart cards" are constructed of a material such as polyester reinforced with glass fibers and have enveloped within the card one or more semiconductor devices. Desirably, such devices should be secured within the card by a die attach adhesive which is flexible but which provides very good adhesive strength and does not impart stress to the die during curing. It is also important that the adhesive be capable of being cured at relatively low temperatures to facilitate fabrication of the cards without damage to the card or the semiconductor devices. Cards including semiconductor devices enveloped therein are disclosed in an article by Hans Steinegger, Microelectronics Manufacturing Technology, pp. 13-15, December 1991; the disclosure of which is expressly incorporated herein by reference. As disclosed in the aforementioned article, the semiconductor devices have heretofore been bonded directly to a metal conductor or other substrate using an epoxy adhesive followed by encapsulation with epoxy resin. The obstacles to the production of such "smart cards" include problems arising in wire bonding because the basic material of the film is not as heat resistant as might be desired. It is pointed out in the article that for smart cards wire bonding must be performed at temperatures that do not exceed 180.degree. C. It is apparent therefor that there is a need for a flexible die attach adhesive which is capable of being cured at relatively low temperatures but has very good adhesive strength. Adhesive formulations have been proposed which are rapidly curing, i.e., are capable of being cured in under 5 minutes at 200.degree. C. However, these formulations contain cyanate esters and are not flexible. The present invention provides a method of rendering cyanate esters flexible by reacting therewith at least one elastomeric and thermo plastic modifier from the group of hydroxyl (-OH), amine (NH) or epoxide reactive groups, or mixtures thereof by, for example, grafting such groups to cyanate molecular structures. Where flexible adhesive formulations with low viscosity are desired for better workability, etc., the cyanate esters are reacted with a polyhydroxyl polymer compound having the formula: In addition to the foregoing, the invention includes adhesive formulation for bonding a semiconductor device to a substrate, which comprises a reaction product of cyanate ester and the elastomeric modifier, as discussed above, having a low glass transition temperature of less than about 25.degree. C. To impart rapid curability at low temperature, the adhesive may include an alkylphenol, a metal-containing curing catalyst, and/or silver in the form of flake or powder. Advantageously, the alkylphenol is nonylphenol, the metal-containing curing catalyst is from the group consisting of cobalt acetylacetonate and copper napthenate and the silver is present in amounts up to 90 wt. %. In one preferred embodiment the adhesive comprises the reaction product of 6 to 24 wt. % modifier and 4 to 16 wt. % cyanate ester, 0.01 to 0.06 wt. % metal-containing curing catalyst, 0.5 to 2 wt. % alkylphenol and up to 90 wt. % silver flake and/or powder. Where alkylphenol and/or metal containing catalyst are present as little as 4 to 20% silver may be sufficient. Where these curing catalysts are absent 60 to 90 wt. % silver may be needed to impart rapid curability to the adhesive formulation. A novel card in accordance with the invention, for processing in a computer, comprises a semiconductor device enveloped within the card and adhered with a flexible adhesive to a substrate. The substrate is advantageously a flexible organic polymeric substrate and/or a lead frame or metal conductor. The adhesive comprises the reaction product of cyanate ester and modifier, as described above, having a glass transition temperature of less than labour 25.degree. C., and which may include an alkylphenol, a metal-containing curing catalyst and/or silver in the form of flake and/or powder.
| Number | Name | Date | Kind |
|---|---|---|---|
| 1743167 | Styer | Jan 1930 | |
| 2895270 | Blaess | Jan 1930 | |
| 3586926 | Nakamura et al. | Jun 1971 | |
| 3595900 | Loudas et al. | Jul 1971 | |
| 3658623 | Grigat et al. | Apr 1972 | |
| 4280885 | Savery | Jul 1981 | |
| 4369302 | Ikeguchi et al. | Jan 1983 | |
| 4375498 | Le Minez et al. | Mar 1983 | |
| 4401776 | Munk | Aug 1983 | |
| 4552690 | Ikeguchi et al. | Nov 1985 | |
| 4604452 | Shimp | Aug 1986 | |
| 4608434 | Shimp | Aug 1986 | |
| 4699888 | Dumesnil et al. | Oct 1987 | |
| 4709008 | Shimp | Nov 1987 | |
| 4732702 | Yamazaki et al. | Mar 1988 | |
| 4740343 | Gaku et al. | Apr 1988 | |
| 4740584 | Shimp | Apr 1988 | |
| 4740830 | Ketley | Apr 1988 | |
| 4754001 | Blahak et al. | Jun 1988 | |
| 4785075 | Shimp | Nov 1988 | |
| 4831086 | Das et al. | May 1989 | |
| 4839442 | Craig, Jr. | Jun 1989 | |
| 4847233 | Shimp | Jul 1989 | |
| 4861823 | Qureshi | Aug 1989 | |
| 4902752 | Shimp | Feb 1990 | |
| 4918157 | Gardner | Apr 1990 | |
| 4931545 | Shimp et al. | Jun 1990 | |
| 4940848 | Shimp | Jul 1990 | |
| 4983683 | Shimp | Jan 1991 | |
| 4999699 | Christie et al. | Mar 1991 | |
| 5002818 | Licari et al. | Mar 1991 | |
| 5036646 | Makihara et al. | Aug 1991 | |
| 5037692 | Medney et al. | Aug 1991 | |
| 5056296 | Ross et al. | Oct 1991 | |
| 5068309 | Shimp | Nov 1991 | |
| 5114003 | Jackisch et al. | May 1992 | |
| 5143785 | Pujol et al. | Sep 1992 | |
| 5149863 | Shimp et al. | Sep 1992 | |
| 5150195 | Nguyen | Sep 1992 | |
| 5155066 | Nguyen | Oct 1992 | |
| 5162574 | Craig, Jr. | Nov 1992 | |
| 5186880 | Gaku et al. | Feb 1993 | |
| 5195299 | Nguyen | Mar 1993 | |
| 5215860 | McCormick et al. | Jun 1993 | |
| 5250600 | Nguyen et al. | Oct 1993 | |
| 5261157 | Chang | Nov 1993 | |
| 5325654 | Juntunen et al. | Jul 1994 | |
| 5330684 | Emori et al. | Jul 1994 | |
| 5399907 | Nguyen et al. | Mar 1995 |
| Number | Date | Country |
|---|---|---|
| 3423385 | Jan 1985 | DEX |
| 153338 | Sep 1983 | JPX |
| 2285968 | Dec 1987 | JPX |
| 3069883 | Mar 1988 | JPX |
| 9208247 | May 1992 | WOX |
| 9316921 | Sep 1993 | WOX |
| 9316987 | Sep 1993 | WOX |
| 9317059 | Sep 1993 | WOX |
| 9324564 | Dec 1993 | WOX |
| 9406844 | Mar 1994 | WOX |
| Entry |
|---|
| D.A. Shimp, et al., "AroCy.RTM. Cyanate Ester Resin, Chemistry, Properties and Applications, " Rh one-Poulenc, Inc.; Jan. 1990, pp. 1-36. |
| E. Grigat and R. Putter, "New Methods of Preparative Organic Chemistry VI-Synthesis and Reactions of Cyanic Esters, " Agnew. Chem. Internat. Edit., vol. 6, Nov. 3, 1967, pp. 206-216. |
| Hi-Tek Polymers, "AroCy.RTM. L-10 Cyanate Ester Monomer, : " Oct. 1989. |
| Hi-Tek Polymers, "AroCy.RTM. Cyanate Ester Resins. " |
| Hi-Tek Polymers, "AroCy.RTM. F-40S Cyanate Ester Resin Solution, " Apr. 1989. |
| Hi-Tek Polymers, "AroCy.RTM. B-10 Cyanate Ester Monomer, " Oct. 1988. |
| Hi-Tek Polymers, "AroCy.RTM. B-40S Cyanate Ester Resin Solution, " Oct. 1988. |
| Hi-Tek Polymers, "AroCy.RTM. B-50 Cyanate Ester Hard Resin, " Oct. 1988. |
| Hi-Tek Polymers, "AroCy.RTM. M-10 Cyanate Ester Monomer, " Oct. 1988. |
| Hi-Tek Polymers, "AroCy.RTM. M-30 Cyanate Ester Semisolid Resin, " Oct. 1988. |
| Hi-Tek Polymers, "AroCy.RTM. M-40S Cyanate Ester Resin Solution, " Oct. 1988. |
| Hi-Tek Polymers, "AroCy.RTM. M-50 Cyanate Ester Hard Resin, " Oct. 1988. |
| Hi-Tek Polymers, "AroCy.RTM. T-30 Cyanate Ester Semisolid Resin, " Oct. 1988. |
| Allied Signal Inc., "Primaset--PT Resins, Safety and Handling Bulletin, " Mar. 20, 1992. |
| Allied Signal Inc., "Primaset--PT Resins. " |
| Allied Signa Inc., "Primaset--PT Resins, Literature List. " |
| Tactix Performance Polymers, "XU-71787.02, XU-71787.07, Developmental Polycyanate Resins for Advanced Composites and Adhesives. " |
| Sajal Das, "Pheno-Triazine (PT) Resin, A New Family of High Performance Thermosets" Cyanate Ester Symposium, Apr. 9-10, 1992. |
| D.A. Shimp and S.J. Ising, "Moisture Effects and their Control in the Curing of Polycyanate Resins, " Cyanate Ester Symposium, Apr. 9-10, 1992. |
| S.L. Simon and J.K. Gillham, "Cure of a Dicyanate Ester/Polycyanurates System, " Cyanate Ester Symposium, Apr. 9-10, 1992. |
| Fraunhofer Institut fur Angewandte Materialforschung, "Polycyanurates and Their Modifications, State of the Art and New Aspects, " Gordon Research Conference on Thermoset, Jun. 1993. |
| Hi-Tek Polymers, "AroCy.RTM. Resins, " Dec. 1988. |
| David Shimp and Mark Southcott, "Controlling Moisture Effects During the Curing to High TG Cyanate Ester/Aramid Composites, " 38th International Symposium and Exhibition, May 10-13, 1993. |
| Rh one-Poulenc, "Specialty Resin--Reactive Rubber Toughners for AroCy.RTM. Cyanate Ester Resins, " Jan. 1991. |
| Rh one-Poulenc, "Specialty Resins--Pyrolysis of AroCy.RTM. Cyanate Esters." |
| Rh one-Poulenc, "Specialty Resins--Quantative Determination of Residual Cyanate in Cured Homopolymers Via FTIR Analysis, " Jan. 2, 1992. |
| Rh one-Poulenc, "Specialty Resins--Compatibility of Cyanate Esters with Aramid Reinforcements and Polyamide/Imide Substrates. " |
| RH one-Poulenc, "Specialty Resins--AroCy.RTM. L-10 Cyanate Ester Monomer, " Sep. 1990. |
| RH one-Poulenc, "Specialty Resins--AroCy.RTM. F-10 Cyanate Ester Monomer, " Sep. 1990. |
| Rh one-Poulenc, "Specialty Resins--AroCy.RTM. M-20 Low Melt Viscosity Prepolymer, " Sep. 1990. |
| Rh one-Poulenc, "Specialty Resins--ArcoCy.RTM. B-10 Cyanate Ester Monomer, " Oct. 1990. |
| Rh one-Poulenc, "Specialty Resins--Toxicity of AroCy.RTM. Cyanate Esters. " |
| Rh one-Poulenc, "Specialty Resins--AroCy.RTM. M-10 Cyanate Ester Monomer, " Sep. 1990. |
| Rh one-Poulenc, "Specialty Resins--AroCy.RTM. Cyanate Ester Resins. " |
| Rh one-Poulenc, "Specialty Resins--AroCy.RTM. Cyanate Ester" List. |
| Rh one-Poulenc, "Specialty Resins--AroCy.RTM. F40-S Cyanate Ester Resin Solution, " Jul. 1990. |
| Rh one-Poulenc, "Specialty Resins--AroCy.RTM. B-30 Cyanate Ester Semisolid Resin. " |
| Rh one-Poulenc, "Specialty Resins--AroCy.RTM. B-40S Cyanate Ester Resin Solution, " Aug. 1990. |
| Rh one-Poulenc, "Specialty Resins--AroCy.RTM. B-50 Cyanate Ester Hard Resin, " Sep. 1990. |
| Rh one-Poulenc, "Specialty Resins--AroCy.RTM. B-40S Cyanate Ester Resin Solution, " Aug. 1990. |
| Rh one-Poulenc, "Specialty Resins--AroCy.RTM. M-30 Cyanate Ester Semisolid Resin, " Sep. 1990. |
| Rh one-Poulenc, "Specialty Resins--AroCy.RTM. M-50 Cyanate Ester Hard Resin, " Sep. 1990. |
| Rh one-Poulenc, "Specialty Resins--AroCy.RTM. Cyanate Ester Safety and Handling Bulletin, " Sep. 1990. |
| Rh one-Poulenc, "Specialty Resins--Formulating ArcOy.RTM. Cyanate Esters for Resin Transfer Molding Applications, " Apr. 1991. |
| Rh one-Poulenc, "Specialty Resins--AroCy.RTM. Cyanate Ester Adhesives for Polyimide Flexible Circuitry, " Jan. 1991. |
| Rh one-Poulenc, "Galvanic Corrosion of Carbon Fiber Composites, " Jan. 1991. |
| Hi-Tek Polymers, "REX-378 Developmental Cyanate Ester Prepolymer. " |
| Uri Sela and Hans Steinegger, "Dispensing Technology-The Key to High-Quality, High-Speed Die Bonding, " Microelectronics Manufacturing Technology, Feb. 1991, pp. 47-52. |
| Jack R. Christenson and David A. Shimp, "Improvements in Performance and Processing Using Cyanate Ester Blends and Alloys, " Ultralloy '90, pp. 191-208. |
| Tony del Rosario, "JM 7000 Low Temperature Die Attach Material Qualification Report, " Olin Interconnect Technologies, Dec. 10, 1992. |
| Malcolm L. White, et al., "Attaining Low Moisture Levels in Hermetic Packages, " IEEE/Proc. IRPS, 1982, pp. 253-259. |
| David P. Galloway and My N. Nguyen, "A New, Reliable Snap Cure Die Attach Adhesive, " May. Res. Soc. Symp. Proc., vol. 264, 1992, pp. 271-280. |
| Sue Oliver, et al., "Silver/Polymer Die Attach for Ceramic Package Assembly, " 1992 IEPS meeting, Sep. 27-30, 1992. |
| My N. Nguyen and Michael B. Grosse, "Low Polymer Moisture Adhesive for Hermetic Packages, " IEEE Trans. on Components, Hybrids and Manufacturing Technology, vol. 15, No. 6, Dec. 1992, pp. 964-971. |
| Richard H. Estes, "A Practical Approach to Die Attach Adhesive Selection, " Hybrid Circuit Technology, Jun. 1991. |
| Tom Ramsey and Gail Heinen, "Controlling Moisture in Ceramic Packages, " Semiconductor International, Aug. 1988. |
| Mitsubishi Gas Chemical Company, Inc., "High Heat Resistant BT Resin--Bismaleimide-Triazine Resin, " Fourth Edition, Sep. 1, 1984. |
| Sue Oliver, "Qualification Status and Extended Stressing of JM7000 Silver/Polymer Die Attach Adhesive for Ceramic Package Assembly, " Jan. 12, 1993. |
| Hi-Tek Polymers, "AroCy.RTM. F-10 Cyanate Ester Monomer, " Apr. 1989. |
| Hi-Tek Polymers, "AroCy.RTM. B-30 Cyanate Ester Semisolid Resin, " Oct. 1988. |
| M. Bauer, J. Bauer and G. K uhn, "Kinetics and modeling of thermal polycyclotrimerization of aromatic dicyanates, " Acta Polymerica 37 (1986), Nr. Nov. 12, pp. 715-719. |
| D.A. Shimp and W.M. Craig, Jr., "New Liquid Dicyanate Monomer for Rapid Impregnation of Reinforcing Fibers, " 34th Int'l SAMPE Symposium, 1989. |
| Hi-Tek Polymers, "AroCy.RTM. Cyanate Ester Safety and Handling Bulletin, Arocy Safety and Handling. " |
| Hans Steinegger, "Smart Cards: Bonding Technology at its Limits, " Microelectronics Mfg. Tech., Dec. 1992, pp. 13-15. |
| Andrew Rosenbaum, "Smarter and Smarter", Electronics, Oct. 1991, 32D & 32E. |
| Daniel Webb, "What Future is in the PC Cards?", Electronic Business, Nov. 4, 1991, p. 11. |
| "Japan Challenges Intel's Lead in Flash memories", attached chart World EPROM Market, Semiconductors. |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 890618 | May 1992 | |
| Parent | 843738 | Feb 1992 |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 392602 | Feb 1995 | |
| Parent | 68794 | May 1993 |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 602504 | Oct 1990 |
